Means for producing alternating currents



Nov. 23 1926. 1,608,292

- H. l. BECKER MEANS FOR PRODUCING ALTERNATING CURRENTS Fig.1.

k E 3 U U E lnventcr A I Howard l. Becker,

MAG-H5712 new by g jw/% fiw n His Attorney.

Nov. 1926.

' 1,608,292 H. l. BECKER MEANS FOR PRODUCING ALTERNATING CURRENTS Filed Feb. 4. 1920 2 Shets-$heet z Howard 1. Becker,

y flaw/k I His Attorney.

Patented Nov. 23, 1926.

UNITED STATES PATENT orries.

HOWARD I. BECKER, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC CO1VI PANY,'A CORPOBATIGN OIE NEW YORK.

MEANS FOR PRODUCING ALTEENATING CURBENTS.

Application filed February 4, 1320. Serial No. 356,269.

My present invention relates to the productlon of alternating currents, and more particularly to the production of continuous high frequency alternating currents such as are commonly employed for radio signaling.

One of the objects of my inventionis to provide a simple and convenient apparatus for producing alternating currents from a direct current source. A more specific object of my invention is to produce continuous high frequency currents suitable for radio signaling from a direct current source or a pulsating source of comparatively low frequency.

In carrying my invention into effect I employ an electron discharge device havlng an electron emitting cathode and an anode enclosed in an evacuated receptacle andpreferably arranged in circular symmetry with respect to each other about an axis. The electrodes of this device are included in a circuit containing a source of current. The current flowing between the two electrodes may be controlled or varied in amplitude by means of a magnetic field in the receptacle in a direction parallel to the axis of the electrodes or at right angles to the electrostatic field between the electrodes. If this magnetic field is varied between certain limits, dependent in each case upon the structure of the device and the voltage applied to the electrodes, the current flowing between the electrodes may be varied between a maximum value which may be the value of the current which would fiow in the absence of any magnetic field and a minimum value whlch may be substantially zero. In practicing my invention it will probably be found desirable in most cases to provide a constant magnetic field of such a value that the current flowing between the electrodes will be somewhat re duced from the amount which would flow in the absence of any magnetic field. The current flowing in the device may then be varied between maximum and minimum values by means of a supplemental variable magnetic field which is produced by means of a current derived from the circuit between the two electrodes and which alternately assist and oppose the constant magnetic field.

A The novel features which I believe to be eharaete invention are set forth. with part is in the appendix? claima- The invention itself, however, both as to its organizatlon and method of operation will best be understood by reference to the fol-' lowing description taken in connection with the accompanying drawing in which Figs. 1, 2, 3, 4 and 5 illustrate diagrammatically various circuit arrangements which may be used in carrying my'invention into effect, and Fig. 6 is a characteristic curve showing the relation between the current flowing between the electrodes at constant voltage and the strength of the magnetic field.

As indicated in the various figures of the drawing, an electron discharge device is employed comprising an evacuated receptacle 1, which is preferably of tubular form and which contains a filamentary cathode 2 and an anode 3 of cylindrical form, these two electrodes in the form of device here indicated being arranged in circular symmetry with respect to each other; that is, the active surfaces of the two electrodes are substantially surfaces of revolutionabout a common axis which is preferably the majoraxis of the receptacle 1. While this arrange ment of electrodes is desirable for securing the best results it is not essential, as satisfactory results may be obtained with arrangements of the electrodes which do not involve circular symmetry. A source of current 4: is connected to the two terminals of the cathode 2 for heating it to incandescence to cause it to emit electrons for carrying current across the evacuated space between the two electrodes. An external circuit between electrodes 2 and 3 includes a source of current 5 for supplying current for the operation of the device. In the present case, the source 5 is indicated as a direct current generator which is preferably shunted by condenser 6 for icy-passing the high frequency components of the currents set u jn' the circuit. This external circuit also contains an. impedance device 7 which is preferably inductive. The constant mag netic field is provided by means of a coil 8 surrounding the receptacle 1, supplied with current from a direct current source 9, the strength of the magnetic field thus fur nished being adjustable to a desired value b'y means of variable resistance 10.

a In the of my inventic indicated in are a i 1 myself to any particular theory or method inductance 11, which is wound around the receptacle 1 and variable capacities 12 and 13, is connected to the terminals of the impedance 7. The oscillatory circuit thus formed is tuned to the frequency of the oscillations which it is desired to produce.

The apparatus which I have indicated and described may be employed in various ways to produce oscillations. and various explanations may be advanced as to the manner in which the apparatus operates to produce oscillations. lVhile I do not wish to limit of operation, the following description is g ven to indicate one way in which the manner of operation of the apparatus may be explained.

lhe relation between the magnetic field and current flowing in the plate or outputcircuit is indicated by the diagram of Fig. 6, the values of the magnetic field being plotted as abscissa; and corresponding current values as ordinates, the impressed voltage being constant. It will be observed that as the strength of the magnetic field is increased from Zero the current remains substantially constant until the magnetic field has reached a value represented by ac. Further increase of field strength produces a rapid reduction of current until at a field strength 06 the current has fallen to substantially Zero.

In the operation of the device to produce oscillations, the constant magnetic field may be adjusted to a value somewhere between the values 0a and 0b. Underthese conditions, when the circuits are completed current will start to flow in the plate circuit. This current will tend to come up to the maximum value possible with the particular field strength to which the constant mag netic field has been adjusted. In building up to this value a potential will be set up across the terminals of the impedance 7 which will cause the condensers of the oscillating circuit to become charged, and when the maximum current value has been reached thesecondensers will discharge through the coil 11 and produce a magnetic field therein which will add to the constant magnetic fielchthereby producing a decrease in current in the plate circuit. The current in the oscillating circuit willthen reversein direction and oppose the constant magnetic field, thereby allowing the current :in the plate circuit to increase. With each change in the current in the plate circuit a variation of potential will be produced across the terminals of the impedance 7, which will cause energy to be supplied to the soil.

lating circuit in such a way as tomaintain oscillationstherein. The oscillating current thus set up in this circuit may be withdrawn therefrom by means of a coupling trans-- former 15 the primary of which is included in the oscillating circuit and the secondary of which supplies the alternating current produced to any desiredutilizationcircuit.

The arrangement indicated in Fig. 2 operates in substantially the same manner as Fig. 1.. It is evident that when potential changes are produced across the impedance 7 corresponding potential changes are pro duced across the electrodes of the device, and in this case the oscillating circuit 1s therefore connected directly across the electrodes of the device.

In Fig. 3 I have indicatedaii arrangement whereby the oscillating currents pioduced may be directly supplied to an antenna 1b. In this case the antenna with its inductance and capacity forins the oscillating circuit and this circuit may conveniently be tuned to the variable inductance 17 as indicated. In case it is desired to employ the currents produced for radio telegraphy. a key 18 may be inserted in the antenna ror.

interrupting the production of high frequency oscillations to produce telegraphic signals.

The ar "angeinent shown in Fig. 4 islequiv alent to that shown in Fig. 1. In this case, however, the o..cillat1ng circuit instead of being directly connected to the term nals of the impedance 7 is inductively connected to this impedance by coupling the coil 19 to impedance 7 whichin thiscase of course will be in the form of an inductance. This is a somewhat more flexible arrangement than that of Fig. 1 in that it permits a ready variation in the mount of energy sup5 plied to the oscillating circuit by varying the coupling between coils? and 19.

The arrangement indicated in Fig. 5 is,

substantially the saine'as that shown in Fig. 4:, only in this case theimpedance 7 is in the form of a coil surrounding the receptacle 1, and the coil 19 is coupled to the coil 7 by also winding this coilarouiid the receptacle 1. In this case I have indicated an antenna 20 as the utilization circuit to which the high frequency currents produced are. suppl ed,

and for purposes of radio telegraphy a key.

18 may beinsertedinthe antenna, as in the arrangement of F1g. 3., lV1th this arrangement the coil7is preferably wound around the receptacle in such a way that the field will alternately assist and oppose the combinedmagnetic fields produced by the other coils and thuscausethe desired increase and decrease inthe current in the plate circuit. hat I claim asnew and desire to secure by Letters iatent of the United States is FM? l. The combination in a system for produc lit) liiii mg alternating currents of an electron discharge device comprising an evacuated receptacle containing an electron emitting cathode and an anode arranged in substantially circular symmetry and unobstructed spacial relation with respect to said cathode, means for producing a constant magnetic lield in said receptacle in the space between said electrodes in a direction substantially at a right angle to the path of electrons between said electrodes, an external circuit between said cathode and anode containing a source of current, an oscillatory circuit connected in shunt relation to said external circuit and means for producing by means of the current flowing in said oscillatory circuit a magnetic field which is in the same direction as and which is supernnposed upon the constant magnetic field.

2. The combination in a system for producing alternating currents of an electron discharge device comprising an evacuated receptacle containing an electron emitting cathode and an anode arranged in substantially circular symmetry and unobstructed spacial relation with respect to said cathode, means for producing a constant magnetic field in said receptacle in the space between said electrodes in a direction substantially at a right angle to the path of electrons between said electrodes, an external circuit between said cathode and anode containing a source of current, and a circuit containing inductance and capacity connected in shunt- .relation to said external circuit, a portion at least of the inductance of said circuit being in the form of a coil surrounding said receptacle and having its major axis substanti ally coincident with the major axis of said electrodes.

3. The combination in a system for producing alternating currents of an electron discharge device comprising an evacuated receptacle containing an electron emitting cathode and an anode arranged in substantially circular symmetry and unobstructed spacial relation with respect to said cathode, means for producing a constant magnetic field in said receptacle in the space between said electrodes in a direction substantially at a right angle to the path of electrons between said electrodes, an external circuit between said cathode and anode containing a source of current, an oscillatory circuit connected in shunt relation to said external circuit and means for producing by means of the current flowing in said oscillatory circnit a magnetic field which is superimposed upon the constant magnetic field and which alternately assists and opposes the constant magnetic field.

4L. The combination in a system for producing alternating currents of an electron discharge device comprising an evacuated receptacle containing an electron emitting cathode and an anode arranged in substantially circular symmetry and unobstructed spacial relation with respect'to said cathode, means for producing a constant magnetic field in said. receptacle in the space between said electrodes in a direction substantially at a right angle to the path ot'electronsbetween said electrodes, an external circuit between said cathode and anode containing a source of current, an auxiliary circuit connected in shunt relation to said external circuit and means for producing by means of the current flowing in said auxiliary circuit a magnetic field which is in the same direction as and which is superimposed upon the constant magnetic field.

5. The combination in a system for producing alternating currents of an electron discharge device comprising an evacuated receptacle containing an electron-emitting cathode and an anode arranged insubstantially circular symmetry and unobstructed spacial relation with respect to said cathode, means for producing a constant magnetic field in said receptacle in the space between said electrodes in a direction substantially at a right angle to the path of electrons between said electrodes, an external circuit between said cathode and anode containing a source of current, an auxiliary oscillating circuit coupled to said external circuit and supplied with energy therefrom, and means for producing by means of the current flowing in said oscillatory circuit a magnetic field whichis in the same direction as and which is superimposed upon the constant magnetic field.

6. The combination in a system for producing alternating currents of an electron discharge device comprising an evacuated receptacle containing a cathode adapted to emit electrons independently of gas ionization, and an anode arranged-in substantially circular symmetry and unobstructed spacial relation with respect to said cathode, an external circuit between said cathode and anode containing a source of current, an auxiliary oscillatory circuit coupled to said external circuit and supplied with energy therefrom, and means for producing by means of the current flowing in said oscillatory circuit a magnetic field in said receptacle in the space between said electrodes in a direction substantially at a right angle to the path of electrons between said electrodes.

7. The combination in a system for producing alternating currents. of an electron discharge device comprising an evacuated receptacle containing a cathode adapted to emit electrons independently of gas ionization, and an anode arranged in substantially circular symmetry and unobstructed spacial relation with respect to said cathode, means for producing a constant magnetic field in the space between said electrodes a diree llll) tion substantially at a right angle to the path of electrons between said electrodes, an external circuit between said cathode and anode containing a source of current, an auxiliary oscillatory circuit coupled to said external circuit and suppliedwvith energy therefrom,

and means for producing by the current flowing in said oscillatory circuit a magnetic field in the space between said electrode in the same direction as theconstant magnetic field.

In Witness whereof, I have hereunto set my hand this 3rd day of February 1920. HO'WARD I. BECKER. 

